Compiling under the closed-world assumption (CWA) has been shown to be an appropriate way for implementing object-oriented languages such as Java on low-end embedded systems. In this paper, we explore the implications of using whole program optimizations such as Rapid Type Analysis (RTA) and coloring on programs targeting the .NET infrastructure. We extended RTA so that it takes into account .Net specific features such as (i) array covariance, a language feature also supported in Java, (ii) generics, whose specifications in .NET impacts type analysis and (iii) delegates, which encapsulate methods within objects. We also use an intraprocedural control flow analysis in addition to RTA . We evaluated the optimizations that we implemented on programs written in C#. Preliminary results show a noticeable reduction of the code size, class hierarchy and polymorphism of the programs we optimize. Array covariance is safe in almost all cases, and some delegate calls can be implemented as direct calls.